


Theory In Practice

by thingswithwings



Category: Avatar: The Last Airbender, Harry Potter - J. K. Rowling
Genre: Crossover, Elemental Magic, F/F, Magic, Quest, Research
Language: English
Status: Completed
Published: 2012-03-11
Updated: 2012-03-11
Packaged: 2017-11-01 18:58:54
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,660
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/360156
Author URL: https://archiveofourown.org/users/thingswithwings/pseuds/thingswithwings
Summary: <blockquote class="userstuff">
              <p>"All right," the young woman says, brushing herself off briskly, apparently undaunted by the half-dozen Water Tribe guards who moved to surround her the moment she came through the portal.  "Take me to your library."</p>
            </blockquote>





	Theory In Practice

**Author's Note:**

  * For [such_heights](https://archiveofourown.org/users/such_heights/gifts), [Aria](https://archiveofourown.org/users/Aria/gifts).



"All right," the young woman says, brushing herself off briskly, apparently undaunted by the half-dozen Water Tribe guards who moved to surround her the moment she came through the portal. "Take me to your library."

Katara is surprised into a smile; this isn't what she expected when she was summoned here to deal with what seemed like a dangerous form of bending. She gestures the guards back and steps forward to offer her hand.

-

There's something about the way Hermione's hair falls into her eyes, and the way she brushes at it, annoyed and ineffectual, for a good ten minutes every time, before finally tying it back with bits of string. And about the way she ties it back with bits of string. And about the way she chews her lip while she reads, occasionally murmuring the words for what she called a translation spell. Katara looks forward to the times she can get away from council meetings and inter-family disputes and border negotiations, just because watching Hermione do research is like a meditative practice. Leading the Southern Water Tribe is good work, worthy and rewarding, but six years of doing little else have left her tired; somehow, Hermione's company makes her feel rejuvenated. It's exciting to be part of a quest again, even if it's not her own.

She likes the research itself, too; she's always wondered about they way bending works, the why and hows of it, and Hermione's approach is just strange enough to be refreshing.

"Elementals, we call them," she tells Katara one day, with an ink brush clutched between her teeth. Her handwriting is still sloppy and inelegant, like that of a child first learning to write, and the characters are strange and incomprehensible to Katara's eyes. "They're part of magical theory where I come from, but here they're the basis for all your magic. I'm hoping that your system can give me a clue about the crisis back home."

Katara frowns, looks down at Hermione's callused fingers where they shift impatiently against the scroll she's reading – an ancient Fire Nation document written by Avatar Huan. "Lack of attention to the balance of the elements could definitely lead to trouble," she agrees. "That's why we have the Avatar, to keep the elements in harmony, and remind us all to do the same. That's part of what went wrong when we went so long without Aang."

Hermione hmmmms, her eyebrows drawing together. "There seem to be some gaps in the record, however."

"The Fire Nation libraries were the least damaged by the recent war, so I brought you here first. But if you want the whole picture, we're going to have to go elsewhere."

At this Hermione looks up from her scroll, blinking as she meets Katara's gaze. "We?" She seems momentarily at a loss for words. "I thought you had obligations back at the South Pole. I thought they couldn't spare you for too long."

"I do have obligations," Katara says, offering Hermione a wry smile. "But there's an old Water Tribe tradition about hospitality to guests, and that obligation supercedes all others. They can spare me for a little while." 

"Oh, I see, it's your duty to take me around to all the finest research institutions in the world," Hermione replies, smiling back. 

"I really have no other choice, much as I'd like to go back."

"Mmmm," Hermione agrees. "What was it you said the council was doing? Fishing treaties?"

"Remarking the borders between fish migration areas that have been in dispute since the end of the war," Katara replies, straight-faced. "It's really a pity I'll have to miss it."

Now Hermione grins at her, reaching across the table to take her hand, and Katara feels warm inside, happy, to be on an adventure again.

-

There are all the Fire Nation libraries, of course, which they navigate with baffled permissions from Zuko and actual help from Mai. Then they move on to the Earth Kingdom government records offices (Katara has never seen anyone so happy to see a well-conceived indexing system in her life, not even Sokka), and while the entrances to the halls of records are zealously guarded, even Earthbenders move aside for Toph. They spend some time pestering Aang for information on where to find the relevant Air Nomad records and histories (carved and painted on the sides of the temples, as it turns out, which Katara wouldn't have expected from Airbenders), and then, after months of travel and information collection and note-taking, Katara can't put it off any longer.

"The ways in which our magic has been breaking down follows these patterns precisely," Hermione says, full of excitement, as they stand on the deck of the Water Tribe ship, leaning together over the railing, heading North. "I really think that the histories of the Water Tribe will give me the last piece of the puzzle."

"It does seem like incorporating elements of bending into your magical practice will help to heal the damage that's been done," Katara agrees. "I can't imagine what it's like for benders – wizards and witches, I mean – to wake up one day and find their bending unreliable. It's horrifying."

Hermione grimaces. "It happened so slowly. We kept putting it down to badly-mixed potions and senility and spells gone awry. But eventually it became clear that there was something wrong with magic itself. With how we used it." She turns to Katara, and her hair whips wildly in the wind, framing her face. "You've taught me so much."

Katara smiles softly and reaches out to the ocean beneath her, the familiar motion of the waves. Idly, she draws up a stream of it and lets it dance for a moment, tendrils flaring out to rainbow mist. "It was there already in your magic," she says, her fingers playing the water like an instrument. "Cauldrons and wands, cups and swords. Snake, Griffon, Badger, Raven. You just needed to go back to your roots." She asks the water to coalesce, then streams it back down to merge with the waves again.

Beside her, Hermione is all air and fire, lost in ideas and talking fast, but Katara can feel the earth in her too, the calm, the cool clarity of water, and she waits, and she wonders.

-

She's seized with anxiety again when they finally reach the North Pole; she wishes she could've found a way to prepare Hermione for this, but the words kept failing her. 

"So, which way to the ancient tomes of knowledge and lore?" Hermione smiles, once the official greetings are over and they're left to their own devices. 

Katara takes Hermione's hand in hers; Hermione looks down, surprised, but says nothing. Her hand is warm in contrast to the cool air around them, reassuring somehow. Katara leads her towards a small, simple tent at the edge of the city.

"It's funny you should ask," she says. "We don't – we don't really have any, is the thing." At Hermione's look of shock and horror, she speaks quickly. "I mean, there are some scrolls, but mostly – mostly – " as she falters, the tent flap is shoved aside and a figure wrapped in fur emerges.

"Mostly we have Gran-Gran," Katara finishes finally. Hermione glances at her and bites her lip.

"Hi," Gran-Gran says. "Call me Kana."

"Hello," Hermione replies, politely.

"It's not that we can't write," Katara adds hurriedly. "Though there are still those in the Fire Nation who say that of us. It's just that – "

"That paper isn't necessarily practical for a tribe of Waterbenders who live in ice palaces hundreds of miles from any trees," Hermione finishes for her, nodding. "I should've guessed. I'm delighted to meet you, Kana. I'm hoping you can help me with this research I'm doing."

"Well, come inside, then," Gran-Gran mutters. "Too cold to stand out jawing in the open air."

Hermione squeezes their clasped hands, and smiles at Katara, and Katara smiles back, relieved.

-

There, in the cold, surrounded by ice and snow, in a place that feels almost like home, Katara finds the courage to do what she's wanted to do for almost a year now, ever since Hermione Granger (Auror First Class, Ministry of Magic, on Special Assignment from the Minister) first stepped through the portal that she made herself, stepped briskly into the unknown in search of aid for her people. She waits for a warm night, when the air between the tents doesn't punish the skin, and goes to Hermione in the dark, bearing a candle before her.

Hermione is poring over a scroll that she practically had to wrestle out of the hands of an Earth Kingdom government librarian, one brush in her hand and one held precariously behind her ear, but she glances up when Katara arrives and offers a surprised smile at the unusual visit.

"Oh, hello," she says. "What brings you here at this hour?"

Katara goes to her, takes away the scroll, sets aside the paper that she was writing on, and removes the brushes from her hand and her hair. There are ink stains on her fingers and one along her cheekbone where she rubbed it the day before, unthinkingly, with the heel of her hand.

"You bring me here," Katara says simply, calmly, and kisses her once. Her lips are dry and her mouth is wet, warm. "Is that all right?"

"Yes," Hermione says, and it sounds like the air escaping from someone who's been punched, like a word spoken out of desperate reflex. She's been lonely, Katara realises, and she regrets not finding the courage to do this earlier. Then Hermione blinks, as if realising what she's just said, and, in her usual confident tone repeats the word, "yes."

Full moon or no, Katara can always feel the blood of her lovers in the heat of passion, feel them pulsing beneath her or above her like a rising tide, but as they move together, shedding clothes, touching, exploring, Katara finds that the rushing of Hermione's blood is different somehow. Hotter. More powerful. Like there really is another kind of magic within her that makes her alien and strange, like her heart moves her blood to a different rhythm than any that Katara has felt before. It's rich, intoxicating.

"You feel amazing," is all she can find it within herself to say, lost in the sensation of Hermione's body against hers, Hermione's hard callused fingers within her and Hermione's hot giving mouth on her skin. "So powerful."

"You – you too," Hermione pants, writhing against her, and if she seems unsure at first, awkward – perhaps? – to be doing this with another woman, she more than makes up for it with the fire in her blood, with the heat behind her eyes, with the passion that drives her to cover Katara's body with her own, to cover every inch of her with touch, with pressure, with the strange sparking lightning that she usually keeps so ruthlessly controlled.

Katara groans, gasps, surrenders to the heat of her. 

She's always had a thing for Firebenders.

-

They spend a month like that, and then two, weeks in which Hermione listens to every tale-teller she can find by day and whispers her new knowledge against Katara's skin at night. Katara keeps up with the latest on the border negotiations, sends her own message hawks regularly to her friends with all the advice and wisdom and commiseration she can muster, but it's in Hermione's bed that she feels most alive, as if, when they're together, her body burns at twice its normal rate.

_We miss you here,_ Sokka writes. _I hope you can come home soon._

-

Hermione isn't the type of person to take any longer at a task than necessary, and Katara isn't the type to ask her to. Her world is suffering, and her people are waiting for her to return with answers. When Hermione's assignment is complete, she asks to be taken back to the South Pole, to the place where their worlds rub up against one another. Neither of them mention the inevitable goodbye; it's unavoidable and they both know it.

"I'll need some help to get back," Hermione says. "My magic is weak here."

"I'll call in the troops," Katara promises, and when they arrive weeks later the others are already there waiting for them: Aang, Toph, Zuko. Sokka's there too, for moral support or just because he's always been convinced that the others can't get anything done without him around to organize and herd them.

"Technically I guess Aang could do this by himself," Katara admits, but Hermione shrugs. 

"Better to have you each concentrating on the element you know best," she says. "Especially as you're going to be channeling that energy through me."

"Putting you in touch with the elemental forces as they affect this world," Aang corrects cheerfully.

"Keeping you grounded," Toph puts in.

"Adding to your power," Zuko grins.

"Bender stuff!" Sokka spreads his hands dramatically, and they all laugh. Hermione's laugh, as always, is bright and full of power. Katara takes care to love it for the last time.

"All right, let's see what we can do," Hermione nods to herself, firmly, and puts her body into the position that Katara taught her, channeling her chi. Katara joins hands with Toph on her left and Zuko on her right, and through Zuko she feels Aang with them too. They each focus their power on Hermione. It's strange, like bending without actually using the physical form of the element – Hermione's form of magic, perhaps, or something approximating it.

It takes a while to build up enough power and to create the right balance to send a person back through, but when she feels it's right Hermione speaks her strange incantations and the portal opens again, shimmering against the blue polar sky like a heat haze that got lost. Katara drops her friends' hands and takes a step towards Hermione just as Hermione takes a step towards her, perfectly in sync. Katara smiles wryly and opens her mouth to say something, but then Hermione's cold hands are cupping Katara's face, and her hot mouth is brushing against Katara's, tentatively at first and then with all the passion they've shared together. 

"I'll come back if I can," Hermione promises, her breath tickling against Katara's face, her cold cheeks. "If we can start healing the magic at home and I'm not so desperately needed, I'll – I'll take a sabbatical and come back."

Katara smiles, then presses the smile to Hermione's mouth, warm and soft. "Or maybe I'll find a way to come there."

Hermione's surprised grin is like a gift, intimate and powerful, and then she takes a step backward, and then another, holding on to Katara's hand for a moment before letting go of that, too, and stepping through the portal.

The shimmer disappears, and Katara is suddenly aware of her friends around her. There's an awkward silence.

"Seems like a nice girl," Toph says eventually. "And she sure gets your heart racing."

Katara blushes as the others laugh, but meets their eyes. "Shut up," she says.

"I bet if we worked on it we could make it to her world," Aang says. "I want to know more about that sport that's played in the air."

"Quidditch," Katara says. She turns to walk back towards the village, and as she does so Zuko throws an arm around her shoulders, another around Aang's.

"And that power source that's made entirely out of lightning," Zuko says.

"Electricity."

Toph shrugs. "I bet they've got some earth there too. I'll go."

"We'll find a way to get there," Sokka says, offering her his most comforting smile. "Count on it. I'll draw up a schedule."

Katara thinks about it the whole way back to the village, and when they get there, she settles in with some paper, tucks an ink brush behind her ear, digs out some of Hermione's collected scrolls, and begins her research.

**Works inspired by this one:**

  * [[Podfic of] Theory In Practice](https://archiveofourown.org/works/763188) by [exmanhater](https://archiveofourown.org/users/exmanhater/pseuds/exmanhater)




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